Crucible furnace



Patented Aug. 23, 1932 UNITED 'STATES PATENT l OFFICE HAROLD' E. WHITE, or ZELIENCPLE, PENNSYLVANIA, AssIeNoR To LAVA CRUCIPLE COMPANY or PITTSBURGH, on PITTsBURGH, PENNSYLVANIA CRUCIBLE EURNACE'k Application led September 29, 1930. Serial No. 485,062.

My invention relates to improvements in Crucible furnaces of the type wherein metals are melted or otherwise treated in Crucibles disposed Within the furnace, the crucibles being heated and the heat transmitted to the f Contained metal by conduction, convection and/or radiation through the walls of the Crucibles.

Furnaces of the Character designated .essentially comprise a Crucible or melting chamber, a Crucible positioned therein and of such dimensions as to provide for the free passage of the heated gases from an associated burner upwardly and around the said Crucible for heating and melting the metal Contained therein. However, due to the uninterrupted passage of the gases upwardly, they do not remain in Contact with the walls of the Crucible a sufficient length of time to produce an eficient heat transfer, resulting in wasted heat and ineiicient operation.

A prime object of this invention is to provide means for increasing the eiciency of such a furnace by effecting a more intimate and prolonged Contact of the heated gases with the walls of the Crucible.

My invention contemplates, in a Crucible furnace, a refractory ramp or inclined floor, so designed and arranged as to conduct the heated gases from a combustion Chamber upwardly and around the Crucible in a whirling or spiral flow, whereby the said gases are brought into intimate Contact with the walls of the Crucible and are maintained in such Contact until discharged from the furnace.

Additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. l is a top plan View of a Crucible furnace embodying my invention;

Figs. 2 and 3 are vertical sectional views taken along the line Ill-II of Fig. l, and looking in opposite directions along said line,

paticularly showing the refractory ramp; an

Y Fig. 4 is a horizontal section taken on the line IV-IV of Fig.'2.

Referring to the drawing, the Crucible furnace A is of the upright Cylindrical type and comprises a hollow refractory body 2 surrounded by an insulating lining 3 and a metal casing 4. The inner wall of the cylindrical refractory body 2 forms a melting chamberv 5' for receiving a Crucible 6, of the usual and well known Construction. Said Crucible is preferably mounted upon al Circular pedestal 7 on the floor a of the melting chamber 5.

An elongated combustion Chamber 8 is positioned adjacent the lower portion of the body 2, tangentially disposed with respect to the cylindrical melting Chamber 5 and in open communication therewith, as at 9. The said Chamber 8 is slightly tapered, and is provided with any suitable oil or gas burner, diagrammatically indicated at 10, at its outer en my invention resides in the construction of Ithe floor of the furnace around the Crucible 6 and its pedestal 7. The floor isconstructed on an inclination or in the form of a Circular ramp ll extending through approximately 360 degrees, or Completely around the melting Chamber. Said ramp may be Constructed of refractory material Vintegrally with the furnace body'2, or may be formed of a separable refractory unit as shown in the of the heated gases from the combustion chamber, and introducing the same onto the An important and characteristic feature of y Y ramp ll. The increasing inclination of the ramp ll is indicated by the increasing number of radial shade lines of Fig. 4.

Thus, the heated gases pass from the combustion chamber 8 onto the ramp 1l and are immediately caused to flow with a whirling motion around the Walls of the Crucible 6, as indicated by the arrows in the drawing. This spiral flow thus induced tends to maintain the gases in Contact with the walls of the Crucible through a greater distance and through a longertime than has heretofore been possible by the straight upward flow in present constructions. In addition to the inclination as above described, the inclined surface of the ramp ll is dished or inclined downwardly and inwardly, thereby causing the gases to literally wrap themselves around the crucible and be maintained in intimate contact therewith.

From the foregoing, it will be seen that the refractory ramp increases the effectiveness of the passage `of the heated gases around the Crucible, and due to the resultant contact of the gases with the walls of the crucible, increases the rate of heat transfer therethrough to provide a more efficient melting furnace.

Various changes and modifications are Contemplated provided they fall within the scope of the following claims.

I claim:

l. In a Crucible furnace, the combination with a hollow body, of a melting chamber therein having a floor, a circular ramp in the floor, and an elongated combustion chamber HAROLD E. WHITE.

exteriorly of the melting chamber in open communication with the melting chamber and tangentially disposed with respect to said ramp to introduce heated gases tangentially onto the upper surface of the ramp, said upper surface being generally spiral and ex- Y tending downwardly and inwardly.

2. In a Crucible furnace, the combination with a hollow body, of a cylindrical melting chamber therein having a floor, a circular pedestal on the floor, a Crucible on the pedestal in spaced relation to the inner wall of the melting chamber, a circular ramp in the floor and around the pedestal, and an elongated combustion chamber eXteriorly of the melting chamber in open communication with the melting chamber for introducing heated gases tangentially directly onto the upper surface of the ramp, said upper surface being generally spiral and also extending downwardly and inwardly to cause the flames to wrap about the crucible.

3. In a crucible furnace, the combination with a cylindrical melting chamber, of an elongated combustion chamber eXteriorly of the melting chamber in open communication with the melting chamber, a ramp initially separate from the melting chamber beginning at the point of communication of the combusllO 

